A digital microwave system mainly completes functions such as mobile backhaul, convergence, and relay. For the reliability of a microwave system, a diversity technology is the most commonly used means currently in the industry. The diversity technology is a method for processing signals of different paths by utilizing different frequencies, separated antennas or a dual-polarized antenna, and reducing or eliminating phase interference by utilizing different routes of an electromagnetic wave at different frequencies, paths or polarization directions. The commonly used diversity technology includes frequency diversity, spatial diversity, and polarization diversity, and its typical block diagram of the principle is shown in FIG. 1. When a first channel and a second channel of a high station/a low station adopt different frequencies, FIG. 1 shows a block diagram of the principle of frequency diversity; when the first channel and the second channel of the high station/the low station adopt a same frequency, and the two antennas adopt the dual-polarized antenna, FIG. 1 shows a block diagram of the principle of polarization diversity; the first channel and the second channel of the low station need to send a cancellation signal to each other for XPIC (cross Polarization Interference Cancellation, cross polarization interference cancellation); and when the first channel and the second channel of the high station/the low station adopt the same frequency, and the two antennas adopt separated antennas, FIG. 1 shows a block diagram of the principle of spatial diversity. The first channel and the second channel are transmission paths of service signals.
The operating principle of a diversity transmission technology shown in FIG. 1 is shown in FIG. 2, and is specifically:
A service 1 and a service 2 are sent to microwave framing units of the first channel and the second channel at the same time, respectively, and the microwave framing units of the first channel and the second channel uniformly place the service 1 and the service 2 in a microwave frame for transmission, that is, service data transmitted in the first channel is the same as that transmitted in the second channel.
The operating principle of a diversity reception technology shown in FIG. 1 is shown in FIG. 3, and is specifically:
Demodulated microwave frame data of the first channel and the second channel is sent to a microwave deframing unit of a diversity reception unit, respectively, and the microwave deframing unit extracts the service 1 and the service 2 from a service data area of the microwave frame, and sends the service 1 and the service 2 to a service selection unit together with a channel quality indication. According to the channel quality indication, the service selection unit selects the service data of the one with better channel quality in the first channel and the second channel for output.
A general format of microwave framing of a diversity transmission unit is shown in the following table.
Microwave FrameMicrowave FrameService DataHeaderOverhead
The microwave frame header is used to identify a microwave frame. The microwave frame overhead is used for microwave channel management, such as alarm backhaul, ATPC (Automatic Transmit Power Control, automatic transmit power control) delivery and the channel quality delivery. The service data is used to load a service section, such as the service 1 and the service 2 which are in FIG. 1.
The existing diversity technology at least has the following disadvantages:
In a processing process of the diversity technology in the prior art, the service data transported in the first channel and the second channel are identical, and channel protection is performed on all services, which leads to a problem of a low spectrum utilization rate when there are a lot of services with low reliability requirements.